How much money should i bring on a 5 day trip to washington dc?

I wouldn't bring nearly that much - maybe $100-$200. You can use a credit card or debit card pretty much everywhere and there are plenty of ATMs in DC if you find you must absolutely have cash.

a 1000 would be just right

if your going with your school, $300. if its just a personal vacation, that depends on where your staying, and where you plan on going.

It depends on where you are staying and what you plan on eating. If you are staying in the city then maybe you'll go back to your room or something to have a bite to eat. If not, then you'll find yourself eating out exclusively. The Air and Space Museum has a McDonald's inside. The Big Mac meal is about $7.50. That's actually pretty cheap for a meal down by the attractions. There are restaurants down in the area but you can expect to pay a good amount for dinner at an actual restaurant. You also want to factor in the Metro to get around and the souvenirs. You may cut it a little close but it is doable. All of this is assuming you are spending freely. I'm extremely cheap. I went to Disney world for a week and spent only $30 bucks on food the entire time. If it wasn't a part of the package then I didn't eat it.

BTW, aside from all the other advice, there's a ALOT of great restaurants out there that won't blow up your wallet, but mind you. DC is a very expensive place unless you're originally from NY, or NJ. Most people will be sticker shocked. http://www.yelp.com/biz/rays-hell-burger-arlington-2 Is a great place that serves gourmet burgers that won't destroy your wallet. I also recommend taking the kids to the DC. Zoo. Its free with no admission charge and remember to bring a Camera. Pack food for your kids in a bookbag so you can give them something healthier than what they will serve you..... Oh and if you have one, Bring a Kite, or a frisbee.